diff --git a/python/functions/ml/tests/test_comfyui_build_pixelart_workflow.py b/python/functions/ml/tests/test_comfyui_build_pixelart_workflow.py
new file mode 100644
index 00000000..d5b88ebc
--- /dev/null
+++ b/python/functions/ml/tests/test_comfyui_build_pixelart_workflow.py
@@ -0,0 +1,99 @@
+"""Tests offline de comfyui_build_pixelart_workflow (sin red ni GPU; estructura del dict)."""
+
+import os
+import sys
+
+sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
+from ml.comfyui_build_pixelart_workflow import comfyui_build_pixelart_workflow  # noqa: E402
+
+
+def _classes(wf):
+    return [n["class_type"] for n in wf.values()]
+
+
+def _ksampler(wf):
+    return next(n for n in wf.values() if n["class_type"] == "KSampler")
+
+
+def test_golden_lcm_two_loras():
+    wf = comfyui_build_pixelart_workflow("isometric house, pixel, 32x32 style", use_lcm=True)
+    cls = _classes(wf)
+    # Dos LoraLoader: SDXL_pixel-art + SDXL_lcm-lora.
+    loras = [n for n in wf.values() if n["class_type"] == "LoraLoader"]
+    assert len(loras) == 2
+    names = {n["inputs"]["lora_name"] for n in loras}
+    assert names == {"SDXL_pixel-art.safetensors", "SDXL_lcm-lora.safetensors"}
+    px = next(n for n in loras if n["inputs"]["lora_name"] == "SDXL_pixel-art.safetensors")
+    assert px["inputs"]["strength_model"] == 1.2
+    # KSampler con defaults LCM.
+    ks = _ksampler(wf)["inputs"]
+    assert ks["steps"] == 8 and ks["cfg"] == 1.5
+    assert ks["sampler_name"] == "lcm" and ks["scheduler"] == "sgm_uniform"
+    assert "CheckpointLoaderSimple" in cls and "SaveImage" in cls
+
+
+def test_edge_no_lcm_single_lora():
+    wf = comfyui_build_pixelart_workflow("a pixel sword", use_lcm=False)
+    loras = [n for n in wf.values() if n["class_type"] == "LoraLoader"]
+    assert len(loras) == 1
+    assert loras[0]["inputs"]["lora_name"] == "SDXL_pixel-art.safetensors"
+    ks = _ksampler(wf)["inputs"]
+    assert ks["steps"] == 25 and ks["cfg"] == 7.0
+    assert ks["sampler_name"] == "euler" and ks["scheduler"] == "normal"
+
+
+def test_edge_overrides_and_clamp():
+    wf = comfyui_build_pixelart_workflow(
+        "pixel knight", use_lcm=True, steps=12, cfg=2.0, lora_strength=5.0
+    )
+    ks = _ksampler(wf)["inputs"]
+    assert ks["steps"] == 12 and ks["cfg"] == 2.0
+    px = next(
+        n for n in wf.values()
+        if n["class_type"] == "LoraLoader" and n["inputs"]["lora_name"] == "SDXL_pixel-art.safetensors"
+    )
+    assert px["inputs"]["strength_model"] == 2.0  # clamp a [0,2]
+
+
+def test_error_empty_prompt():
+    try:
+        comfyui_build_pixelart_workflow("   ")
+        assert False, "deberia lanzar ValueError"
+    except ValueError as e:
+        assert "positive" in str(e)
+
+
+def test_determinism():
+    a = comfyui_build_pixelart_workflow("pixel cat", seed=3)
+    b = comfyui_build_pixelart_workflow("pixel cat", seed=3)
+    assert a == b
+
+
+def test_transparent_default_injects_rembg():
+    """transparent default True -> nodo Image Rembg y SaveImage repuntado a el."""
+    wf = comfyui_build_pixelart_workflow("pixel knight, full body")
+    rembg = [n for n in wf.values() if n["class_type"] == "Image Rembg (Remove Background)"]
+    assert len(rembg) == 1
+    assert rembg[0]["inputs"]["transparency"] is True
+    assert rembg[0]["inputs"]["model"] == "u2net"
+    # SaveImage debe leer de la salida del Rembg, no del VAEDecode.
+    rembg_id = next(k for k, n in wf.items() if n["class_type"] == "Image Rembg (Remove Background)")
+    save = next(n for n in wf.values() if n["class_type"] == "SaveImage")
+    assert save["inputs"]["images"][0] == rembg_id
+
+
+def test_transparent_false_no_rembg():
+    """transparent=False -> sin nodo Rembg (tiles/fondos opacos)."""
+    wf = comfyui_build_pixelart_workflow("seamless grass tile", transparent=False)
+    rembg = [n for n in wf.values() if n["class_type"] == "Image Rembg (Remove Background)"]
+    assert len(rembg) == 0
+    # SaveImage lee directo del VAEDecode.
+    vae_id = next(k for k, n in wf.items() if n["class_type"] == "VAEDecode")
+    save = next(n for n in wf.values() if n["class_type"] == "SaveImage")
+    assert save["inputs"]["images"][0] == vae_id
+
+
+def test_rembg_model_override():
+    wf = comfyui_build_pixelart_workflow("anime hero", rembg_model="isnet-anime")
+    rembg = next(n for n in wf.values() if n["class_type"] == "Image Rembg (Remove Background)")
+    assert rembg["inputs"]["model"] == "isnet-anime"
diff --git a/python/functions/ml/tests/test_comfyui_pixelize_image.py b/python/functions/ml/tests/test_comfyui_pixelize_image.py
new file mode 100644
index 00000000..d5de7853
--- /dev/null
+++ b/python/functions/ml/tests/test_comfyui_pixelize_image.py
@@ -0,0 +1,147 @@
+"""Tests de comfyui_pixelize_image (offline, sin red ni GPU; PIL/numpy)."""
+
+import os
+import sys
+
+import numpy as np
+from PIL import Image
+
+sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
+from ml.comfyui_pixelize_image import comfyui_pixelize_image  # noqa: E402
+
+
+def _noisy_png(path, w=256, h=256):
+    """PNG ruidoso con cientos de colores (simula crudo borroso de IA)."""
+    rng = np.random.default_rng(7)
+    arr = rng.integers(0, 256, size=(h, w, 3), dtype=np.uint8)
+    Image.fromarray(arr, "RGB").save(path)
+    return path
+
+
+def test_golden_downscale_quantize(tmp_path):
+    src = _noisy_png(str(tmp_path / "raw.png"))
+    dst = str(tmp_path / "pixel.png")
+    res = comfyui_pixelize_image(src, dst, downscale=8, colors=16)
+    assert res["ok"] is True, res["error"]
+    assert os.path.isfile(dst)
+    assert res["size"] == [256, 256]          # upscale_back=True conserva tamano
+    assert res["n_colors_final"] <= 16        # cuantizado a <=16 colores
+
+
+def test_no_upscale_back_keeps_small(tmp_path):
+    src = _noisy_png(str(tmp_path / "raw.png"))
+    dst = str(tmp_path / "small.png")
+    res = comfyui_pixelize_image(src, dst, downscale=8, colors=16, upscale_back=False)
+    assert res["ok"] is True
+    assert res["size"] == [32, 32]            # 256//8
+
+
+def test_edge_fixed_palette_game_boy(tmp_path):
+    src = _noisy_png(str(tmp_path / "raw.png"))
+    dst = str(tmp_path / "gb.png")
+    res = comfyui_pixelize_image(src, dst, palette="game-boy")
+    assert res["ok"] is True, res["error"]
+    assert res["n_colors_final"] <= 4         # paleta Game Boy = 4 colores
+
+
+def test_edge_palette_list_hex(tmp_path):
+    src = _noisy_png(str(tmp_path / "raw.png"))
+    dst = str(tmp_path / "pal.png")
+    res = comfyui_pixelize_image(src, dst, palette=["#000000", "#ffffff", "#ff0000"])
+    assert res["ok"] is True
+    assert res["n_colors_final"] <= 3
+
+
+def test_edge_downscale_1_only_quantizes(tmp_path):
+    src = _noisy_png(str(tmp_path / "raw.png"))
+    dst = str(tmp_path / "q.png")
+    res = comfyui_pixelize_image(src, dst, downscale=1, colors=8)
+    assert res["ok"] is True
+    assert res["size"] == [256, 256]
+    assert res["n_colors_final"] <= 8
+
+
+def test_error_missing_src(tmp_path):
+    res = comfyui_pixelize_image(str(tmp_path / "nope.png"), str(tmp_path / "o.png"))
+    assert res["ok"] is False
+    assert "no existe" in res["error"]
+
+
+def test_error_downscale_zero(tmp_path):
+    src = _noisy_png(str(tmp_path / "raw.png"))
+    res = comfyui_pixelize_image(src, str(tmp_path / "o.png"), downscale=0)
+    assert res["ok"] is False
+    assert "downscale" in res["error"]
+
+
+def test_error_bad_palette(tmp_path):
+    src = _noisy_png(str(tmp_path / "raw.png"))
+    res = comfyui_pixelize_image(src, str(tmp_path / "o.png"), palette="not-a-palette")
+    assert res["ok"] is False
+    assert "paleta" in res["error"].lower()
+
+
+# --- alpha-aware (sprites con fondo transparente) ---
+
+def _rgba_subject_png(path, canvas=256, box=120):
+    """RGBA: sujeto opaco de colores variados centrado, fondo transparente."""
+    rng = np.random.default_rng(3)
+    arr = np.zeros((canvas, canvas, 4), dtype=np.uint8)
+    o = (canvas - box) // 2
+    arr[o:o + box, o:o + box, :3] = rng.integers(0, 256, size=(box, box, 3), dtype=np.uint8)
+    arr[o:o + box, o:o + box, 3] = 255  # sujeto opaco
+    Image.fromarray(arr, "RGBA").save(path)
+    return path
+
+
+def test_alpha_preserved_transparent_corners(tmp_path):
+    """RGBA in -> RGBA out con esquinas transparentes y paleta limitada en lo opaco."""
+    src = _rgba_subject_png(str(tmp_path / "sprite.png"))
+    dst = str(tmp_path / "px.png")
+    res = comfyui_pixelize_image(src, dst, downscale=4, colors=16, upscale_back=False)
+    assert res["ok"] is True, res["error"]
+    assert res["has_alpha"] is True
+    out = Image.open(dst).convert("RGBA")
+    a = np.asarray(out)[..., 3]
+    w, h = out.size
+    # Las 4 esquinas deben ser transparentes (alpha == 0).
+    assert a[0, 0] == 0 and a[0, w - 1] == 0
+    assert a[h - 1, 0] == 0 and a[h - 1, w - 1] == 0
+    # Centro opaco.
+    assert a[h // 2, w // 2] == 255
+    # Colores limitados en la zona opaca.
+    assert res["n_colors_final"] <= 16
+
+
+def test_alpha_off_flattens_to_rgb(tmp_path):
+    """keep_alpha=False sobre RGBA -> sale RGB (sin canal alpha)."""
+    src = _rgba_subject_png(str(tmp_path / "sprite.png"))
+    dst = str(tmp_path / "flat.png")
+    res = comfyui_pixelize_image(src, dst, downscale=4, colors=16, keep_alpha=False)
+    assert res["ok"] is True
+    assert res["has_alpha"] is False
+    assert Image.open(dst).mode != "RGBA"
+
+
+def test_rgb_input_unaffected_by_keep_alpha(tmp_path):
+    """Imagen RGB (sin alpha) con keep_alpha=True sigue saliendo RGB, sin romper."""
+    src = _noisy_png(str(tmp_path / "raw.png"))
+    dst = str(tmp_path / "rgb.png")
+    res = comfyui_pixelize_image(src, dst, downscale=8, colors=16)  # keep_alpha default True
+    assert res["ok"] is True
+    assert res["has_alpha"] is False
+    assert res["n_colors_final"] <= 16
+
+
+def test_error_all_transparent_no_crash(tmp_path):
+    """RGBA toda transparente (rembg sin sujeto): no crashea, 0 colores opacos."""
+    arr = np.zeros((64, 64, 4), dtype=np.uint8)  # alpha 0 en todo
+    src = str(tmp_path / "empty.png")
+    Image.fromarray(arr, "RGBA").save(src)
+    dst = str(tmp_path / "out.png")
+    res = comfyui_pixelize_image(src, dst, downscale=1, colors=16)
+    assert res["ok"] is True, res["error"]
+    assert res["has_alpha"] is True
+    assert res["n_colors_final"] == 0
+    out = np.asarray(Image.open(dst).convert("RGBA"))
+    assert out[..., 3].max() == 0  # sigue toda transparente
diff --git a/python/functions/ml/tests/test_crop_to_content.py b/python/functions/ml/tests/test_crop_to_content.py
new file mode 100644
index 00000000..d22ad6ff
--- /dev/null
+++ b/python/functions/ml/tests/test_crop_to_content.py
@@ -0,0 +1,112 @@
+"""Tests de crop_to_content (offline, sin red ni GPU; PIL/numpy)."""
+
+import os
+import sys
+
+import numpy as np
+from PIL import Image
+
+sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
+from ml.crop_to_content import crop_to_content  # noqa: E402
+
+
+def _rgba_subject_in_corner(canvas=256, box=40, ox=8, oy=8):
+    """RGBA con un rectangulo opaco rojo en una esquina, resto transparente."""
+    arr = np.zeros((canvas, canvas, 4), dtype=np.uint8)
+    arr[oy:oy + box, ox:ox + box, 0] = 220   # R
+    arr[oy:oy + box, ox:ox + box, 3] = 255   # alpha opaco
+    return Image.fromarray(arr, "RGBA")
+
+
+def _rgba_subject_centered(canvas=256, fill_ratio=0.9):
+    """RGBA con un rectangulo opaco que llena ~fill_ratio del lienzo, centrado."""
+    arr = np.zeros((canvas, canvas, 4), dtype=np.uint8)
+    side = int(canvas * fill_ratio)
+    o = (canvas - side) // 2
+    arr[o:o + side, o:o + side, 1] = 200     # G
+    arr[o:o + side, o:o + side, 3] = 255
+    return Image.fromarray(arr, "RGBA")
+
+
+def _rgb_subject_on_bg(canvas=200, box=50, ox=10, oy=10, bg=(255, 255, 255)):
+    """RGB con un cuadrado de color sobre fondo plano (sin alpha)."""
+    arr = np.zeros((canvas, canvas, 3), dtype=np.uint8)
+    arr[:, :] = bg
+    arr[oy:oy + box, ox:ox + box] = (0, 0, 200)  # sujeto azul
+    return Image.fromarray(arr, "RGB")
+
+
+def _alpha_bbox_coverage(img, threshold=10):
+    """Fraccion del lado que ocupa el bbox del contenido (alpha>threshold)."""
+    a = np.asarray(img.convert("RGBA"))[..., 3]
+    ys, xs = np.where(a > threshold)
+    if xs.size == 0:
+        return 0.0
+    bw = xs.max() - xs.min() + 1
+    bh = ys.max() - ys.min() + 1
+    return max(bw, bh) / max(img.size)
+
+
+def test_golden_corner_subject_fills_frame():
+    """Sujeto en la esquina -> tras crop ocupa casi todo el frame (square)."""
+    img = _rgba_subject_in_corner()
+    before = _alpha_bbox_coverage(img)
+    out = crop_to_content(img, pad_ratio=0.06, square=True)
+    after = _alpha_bbox_coverage(out)
+    assert out.mode == "RGBA"
+    assert out.size[0] == out.size[1]          # cuadrado
+    assert before < 0.25                       # antes diminuto
+    assert after >= 0.80                       # despues llena el frame
+
+
+def test_edge_centered_subject_not_overcropped():
+    """Sujeto ya centrado que llena ~90%: la cobertura se mantiene alta, no se rompe."""
+    img = _rgba_subject_centered(fill_ratio=0.9)
+    out = crop_to_content(img, pad_ratio=0.06, square=True)
+    assert out.size[0] == out.size[1]
+    assert _alpha_bbox_coverage(out) >= 0.80
+
+
+def test_edge_rgb_background_bbox():
+    """RGB con fondo plano: detecta el sujeto por diff-fondo y lo cuadra."""
+    img = _rgb_subject_on_bg()
+    out = crop_to_content(img, pad_ratio=0.05, square=True)
+    assert out.mode == "RGB"
+    assert out.size[0] == out.size[1]
+    # El sujeto azul debe ocupar buena parte del lienzo recortado.
+    arr = np.asarray(out)
+    is_subject = (arr[..., 2] > 120) & (arr[..., 0] < 80)
+    cov = is_subject.sum() / (out.size[0] * out.size[1])
+    assert cov >= 0.4
+
+
+def test_edge_no_square_only_crops():
+    """square=False: recorta al bbox + margen, sin forzar cuadrado."""
+    img = _rgba_subject_in_corner(box=40)
+    out = crop_to_content(img, pad_ratio=0.0, square=False)
+    # bbox del sujeto es 40x40 -> sin pad ni cuadrar, sale 40x40.
+    assert out.size == (40, 40)
+
+
+def test_error_all_transparent_returns_copy():
+    """Imagen toda transparente: no crashea, devuelve copia intacta (mismo tamano)."""
+    arr = np.zeros((128, 128, 4), dtype=np.uint8)  # alpha 0 en todo
+    img = Image.fromarray(arr, "RGBA")
+    out = crop_to_content(img)
+    assert out.size == (128, 128)
+    assert np.asarray(out)[..., 3].max() == 0
+
+
+def test_error_none_raises():
+    try:
+        crop_to_content(None)
+        assert False, "deberia lanzar ValueError"
+    except ValueError as e:
+        assert "None" in str(e)
+
+
+def test_does_not_mutate_input():
+    img = _rgba_subject_in_corner()
+    snapshot = np.asarray(img).copy()
+    crop_to_content(img)
+    assert np.array_equal(np.asarray(img), snapshot)